Comparison Of Sevoflurane With Propofol In Potentiation For Potency And Neuromuscular Effect Of Cisatracurium

ObjectiveCisatracurium is a benzylisoquinolinnium non-depolarizing neuromuscular blocking agent with intermediate duration of action and non-cumulation.In clinical practice,it is commonly administered in combination with the volatile agents, especially sevoflurane.Preliminary studies suggest that volatile agents potentiate the action of muscle relaxants.However,variability between subjects may confound these comparisons.Furthermore,to quantify the enhancement of the neuromuscular block produced by potent inhalation anaesthetics,it is important to start the investigation after adequate time has elapsed for sevoflurane to diffuse into the muscular compartment.So a randomized study was performed in the patients to investigate the dose-response relationship and the neuromuscular effect of cisatracurium under either sevoflurane or propofol anesthesia.MethodsNinety ASAâ… orâ…¡patients were included,aged 18 to 60 years.A single-dose technique and the single-twitch mode of stimulation(acceleromyography, TOF-Watch(?) SX) were used in the potency estimation part of the study.Forty-eight patients were induced with midazolam 0.05mg/kg,fentanyl 2μg/kg and propofol onset concentration 2μg/ml,target concentration 4μg/ml.Tracheal intubation was performed under 2%lidocaine local asperse without the aid of neuromuscular blocking agents and anaesthesia was maintained according to a table of random number with sevoflurane(1.3MAC of end-tidal concentration,age adjusted) or propofol 2-3μg/ml.Standard hemodynamics,end-tidal CO₂,and anesthetic gas concentrations were monitored continuously.After 40 minutes,a randomized dose (12.5,25,37.5 or 50μg/kg) of cisatracurium was administered.Maximal depression of the twitch response was recorded to calculate the dose-response curve.It was determined by least squares linear regression of the logarithm of each dose against a probit transformation of the initial dose and response of each patient.The effective dose to obtain 50%and95%neuromuscular block(ED₅₀ and ED₉₅,respectively) were calculated from individual dose-response curves.The action duration and recovery of cisatracurium 0.2mg/kg was determined in the other 42 subjects.Anaesthesia was induced with propofol TCI(target-controlled infusion),fentanyl 2μg/kg and cisatracurium 0.2mg/kg.Tracheal was intubated when maximal neuromuscular blocking achieved.Patients in the sevoflurane group were maintained with 1.3MAC sevoflurane of end-tidal concentration and 0.1-0.3μg/kg/min remifentanil,while maintained with propofol TCI 2-3μg/ml and 0.1-0.3μg/kg/min remifentanil in the propofol group.Core temperature and skin temperature over the thenar muscle were monitored and maintained at greater than 36.0℃and 32.0℃,respectively,by forced-air warming.The heart rate and blood pressure in the range of±30%of the basic line.The TOF mode of stimulation was used.The variables recorded were as follows:onset time(time from drug administration to maximum effects),no-response time(disappearance of T₁ to appearance of T₁),times to recovery of T₁ to 25% and75%of control,recovery index(time from T₁ 25%to 75%) and the TOF ratio to 25%.The results of this part were analyzed using the Student's t test.P<0.05 was considered significant.ResultsMean ED₅₀ and ED₉₅(95%confidence interval) of cisatracurium were 26(range, 12-43) and 62(46-87)μg/kg in the propofol group,while they were 15(9-36) and 39 (25-52)μg/kg in the sevoflurane group.There were statistically significant differences in ED₅₀ and ED₉₅ between the two groups.In the dose of 0.2mg/kg of cisatracurium, TOF ratio 0.25 and recovery index were longer during sevoflurane anesthesia than that of propofol anesthesia:(66.60±9.92) vs(58.72±9.74) min,(21.70±5.50) vs(13.43±3.35) min,respectively(P<0.05).There were no differences in onset time, no-response time and 25%recovery time between the two groups:(190.35±25.50) vs(188.21±29.71)sec,(40.06±7.91) vs(42.85±7.50)min,(52.27±10.26) vs(55.49±9.75)min,respectively.ConclusionsIn ASAâ… orâ…¡Chinese adult patients,ED₅₀ and ED₉₅ of cisatracurium are significantly decreased under 1.3MAC sevoflurane anesthesia compared with propofol anesthesia with single-dose method.Recovery time in a single dose of 0.2mg/kg of cisatracurium is longer under 1.3MAC sevoflurane and remifentanil anaesthesia than under stable propofol TCI and remifentanil anaesthesia.It shows that 1.3MAC sevoflurane potentiates the potency and neuromuscular effect of cisatracurium.